Interesting but disappointing. The story of a vanished polar expedition and the semi-supernatural terror that persecuted it.
I still think it's an interesting concept and the story had potential, but the execution was lacking. For one, although I have nothing against long books in theory, this one actually felt like it could have been shaved down. I kept mentally editing portions of it, especially some of the flashbacks to England or around the south polar expedition with Sophia. By that, I mean I was thinking things like: it'd be much more effective if you cut most of this scene and just keep this small part for the emotional impact with a few details for weight...etc. You may disagree with how much this needed to be done, but I feel the narrative could have been tightened up a lot.
The jumping around in time at the beginning managed to cut more tension than it managed to build. I'm not saying the story should have been told in chronological order, but I was left with the impression that if you took a bunch of sticky notes and laid them out, a better order could have been found in which to present them (while shaving down sequences). I didn't care enough to attempt this, however. Btw, I never felt that the descriptions of the cold should have been cut. Those were all relevant.
Maybe this is a personal failing, but I had a hard time working out where things were happening on the map provided. And a list of the dramatis personae would have been helpful. And Simmons just had to work in the rosy-fingered dawn reference. Was anyone else tempted to call him an erudite bastard at a few points?
Oh, and one final complaint: the use of the journal entries was fine (although I was skeptical of the logic of some of the capitalization), but the reproduction of whole scenes of dialogue just did not work well in the journal format.
I'll end on one thing that did work well: the structure of the prose in some of the drunk or dream/sleep-deprivation sequences. It managed to convey that dreamy state.